Mitch McConnell, the minority leader, accused Democrats of an “incredible abuse of power” and of running the country like a “banana republic.” The Republican said he was discouraged to “see the way the United States Senate deteriorated under the current leadership.”

McConnell proposed that Reid drop his demands that the Senate approve a slate of what the Republican leader called “non-urgent” presidential nominees.

“I object,” Reid answered.

Reid asked that the Senate take up a tax bill passed by the House.

“I object,” McConnell replied.

In retrospect, how could it have been otherwise? These aren’t conventional political rivals we’re talking about. They are more like warring mafia families. James Gandolfini may have left us in 2013, but the spirit of the mob boss still dominates in the Capitol. Not only is it legal to put contracts out on each other, it is expected.

The political killings are accomplished by syndicates known as the National Republican Senatorial Committee (NRSC) and the Democratic Senatorial Campaign Committee (DSCC), run by the senators themselves with the goal of unseating rivals across the aisle: not just disagreeing with them, but taking them out. (Similar committees exist in the House, but it’s less of a problem there because district lines have left so few incumbents in jeopardy.)

Earlier this month, when bipartisanship was still in the air, Reid told Bloomberg’s Al Hunt that he wouldn’t campaign against McConnell, who is facing a difficult reelection. “I’m a traditionalist here, and that isn’t anything I’ve ever done and will not do,” Reid said.

That was a bit disingenuous, because Reid had already hosted a fundraiser in Las Vegas for McConnell’s Democratic opponent, and Reid’s political action committee had already given her money. The candidate, Alison Lundergan Grimes, would probably be hurt politically by appearing with Reid, anyway.

But in calling himself a traditionalist, Reid was arguing against the mafia culture that has gripped the Senate since 2004, when Bill Frist, then the Republican leader, went to South Dakota to campaign, successfully, for the defeat of then-Minority Leader Tom Daschle. The DSCC, under Sen. Chuck Schumer of New York, retaliated by running TV ads targeting McConnell in 2008. In 2012, the NRSC, run by Sen. John Cornyn of Texas, raised money to try to defeat Reid in Nevada. The political committees are under the de facto control of the majority or minority leader, and several senators have used the chairmanships as steppingstones to leadership.

When they aren’t ordering hits on each other, the senators use the committees to taunt each other. Monday morning, the Republican committee issued a statement saying: “Harry Reid will tell you he’s not concerned about losing the majority — hell, Reid will say just about anything on most days, but his actions speak louder than his words.” Wednesday, the Republican group declared: “Vulnerable incumbent Senate Democrats — from Kay Hagan to Jeff Merkley, Mary Landrieu to Mark Pryor, Jeanne Shaheen to Mark Begich all lied to their constituents.”

When your day starts with trash talk from people who are trying to kill you politically, is it any wonder things quickly devolve?

Reid, on the Senate floor this week, accused Republicans of “hostage-taking” and ridiculed McConnell for delaying what the GOP leader called “non-essential” confirmations: “Does the Republican leader consider the secretary of the Department of Homeland Security — the individual tasked with protecting us from terrorist attacks — ‘non-essential’?”

McConnell, in turn, told reporters he “can’t imagine” Republicans would agree to increase the debt limit without more spending restrictions. And he delivered a broadside against Reid for stripping Republicans’ right to filibuster nominees: “As we end the year, it’s a tragedy the way the Senate is being run into the ground by basically one person. . . . It’s going to be hard to get the Senate back to normal.”